U.S. Pat. No. 3,997,239 discloses a microscope consisting of shell shaped parts. The microscope stage is attached to an arm and by means of an eccentric disk can be moved in the direction of the optical axis of the microscope. Artificial illumination for the objects on the microscope stage is not provided. Moreover, the shaping of the shells also provides a tube sleeve for the microscope stage. The tube itself together with the optics can be inserted into the tube sleeve. The optical axis of the tube is perpendicular to the surface of the microscope stage. Furthermore, the shells carry a turret with objectives the optical axes of which are parallel to the optical axis of the tube. By the vertical arrangement of the tube, no attention is paid to the user's viewing ergonomy.
U.S. Pat. No. 4,361,377 also describes a portable and compact microscope that on the housing is provided with a multiplicity of setting elements. The specimen to be examined is introduced through a slot in the housing. Illumination is provided by a conventional incandescent lamp that can be connected to a battery acting as the power supply. The housing consists of two shells connected to each other by a screw. The microscope disclosed by this patent is quadrangular, and the specimen holders to be examined are pushed into the housing. The microscope does not have the conventional C-shaped stand and it also does not permit the examination of specimens on different specimen holders, because the microscope stage is not adjustable.
U.S. Pat. No. 5,844,714 discloses a portable microscope that must be assembled from a multitude of individual components in order to be able to view an object. The object is fastened to a swivelable arm so that focusing can be achieved by appropriate swiveling. The microscope is difficult to handle, and furthermore the risk exists that some components may get lost. This microscope is not suited for fast and routine examinations.
U.S. Pat. No. 5,127,614 discloses a microscope stand built on the modular principle. The column and the arm which, for example, carries the tube are cast components. The base of the stand is designed so that it surrounds the column. The microscope proposed in this patent, however, is not intended to be a portable microscope.